Currently, the wear resistance, slidability, and fracture resistance of members, such as cutting tools, wear resistant members, and slidable members, requiring high wear resistance, slidability, and fracture resistance are increased by forming coating layers on the surfaces of base bodys each made of a sintered alloy such as a ultra-hard alloy or a cermet, a sintered compact having high hardness such as diamond or cubic boron nitride (cBN), or ceramics such as alumina or silicon nitride.
In addition, nitride layers mainly made of Ti or Al have been actively studied through physical vapor deposition such as arc ion plating or sputtering and have been continuously improved for extending the life of tools. In addition to the coating material elements, these surface-covered tools have been variously contrived for corresponding to changes in the cutting environment, such as an increase in cutting speed, and diversification of work materials.
For example, Japanese Unexamined Patent Application Publication No. 2008-264975 discloses a surface-covered tool including a film of, for example, TiAlN formed on a surface of a base body wherein the ratio of Ti in the flank face is larger than that in the rake face. Japanese Unexamined Patent Application Publication No. 2002-346812 discloses a hard TiAlN film having a thickness of 1 to 5 μm formed on a surface of a base body material and including coarse particles having a size larger than the thickness of the hard film in an amount of 5% by area or less to give a surface roughness Ra of 0.1 μm or less or a surface roughness Rz of 1 μm or less. Japanese Unexamined Patent Application Publication No. 2005-271155 discloses a coating film having a composition of, for example, (AlCrV)N, formed on a surface of a base body material and reducing the number of microparticles present on the surface of the coating film.    The following is a list of the aforementioned background art
PTL 1: Japanese Unexamined Patent Application Publication No. 2008-264975
PTL 2: Japanese Unexamined Patent Application Publication No. 2002-346812
PTL 3: Japanese Unexamined Patent Application Publication No. 2005-271155